Almost every graph question is one of four little jobs. Spot which one it's asking and the rest is just reading heights — the skill you locked in last rung.
The Four Jobs
Highest — find the tallest bar; its label is your answer. Lowest — find the shortest one. Total — read every bar and add them up. Difference — read two bars and subtract the smaller from the bigger. That's it. The word in the question (most, fewest, altogether, how much more) quietly tells you which job it is.
A Worked One
Say a graph shows books read each month — Jan 4, Feb 7, Mar 3, Apr 9, May 6, Jun 5. "How many more in April than March?" That's a difference. Read April (9), read March (3), subtract: 9 − 3 = 6 more books. "How many altogether?" is a total: 4+7+3+9+6+5 = 34. Same graph, different job, same reading skill.
Trend Questions
On a line graph you'll also get trend questions — "what happened over time?" Don't read a single point; read the shape. Going uphill means rising, downhill means falling, flat means steady. A line graph is built for this because the line literally draws the journey for you.